The active carbon possesses a large specific surface area and exhibits a great ability to effect adsorption and finds utility as a representative adsorbent in various applications. When the active carbon is directly ingested into the digestive system as a medicinal carbon for the purpose of removing by adsorption such substances as induce autointoxication, medicinal poisoning, etc. however, it is liable to do harm by causing constipation. When an effort is made to mingle the active carbon with a foodstuff and ingest the mixture into the digestive system, it is at a disadvantage in imparting an unpleasant sensation to the palate and smearing the foodstuff in a blackish tint. It is also known that in the animal cell, the active carbon in a finely divided state is adsorbed on the protein or sugar protein in the outer layer of the cell membrane. When the active carbon in the finely divided state is directly ingested into the digestive system as an agent for the removal of a harmful substance by adsorption, it is suspected that part thereof persists in a state adsorbed on the cells in the digestive system with fastness such that thorough elimination thereof from the digestive system may be extremely difficult.
With a view to solving this problem, adsorbents formed by coating active carbon with water-insoluble mannan such as konjak or with a cross-linked polymer such as calcium alginate have been proposed (JP-A-55-95,611 and JP-A-04-210,239). Since these adsorbents result from forming a surface coat on the particles of active carbon, they suffer from such problems as inducing a decrease in the surface area and impeding ample manifestation of the ability of adsorption inherent in the active carbon.
This invention has been created in the light of the problem encountered by the prior art as described above. It has for an object thereof the provision of an adsorbent which keeps intact the ability of adsorption inherent in the adsorption basis such as of active carbon and, on being brought into direct contact with foodstuffs or ingested directly into the digestive system, effects highly efficiently the removal by adsorption of such harmful substances as are suffered to adhere to or mingle into the foodstuffs or suffered to occur in the digestive system.